Revision of the 'Acanthephyra purpurea' species complex (Crustacea: Decapoda), with an emphasis on species diversification in the Atlantic.

We inventoried all nine species of the 'Acanthephyra purpurea' complex, one of the most abundant and cosmopolitan group of mesopelagic shrimps. We used 119 specimens at hand and genetic data for 124 specimens from GenBank and BOLD. Phylogenetic analysis of four genes (COI, 16S, NaK, and enolase) showed that the 'Acanthephyra purpurea' complex is polyphyletic and encompasses two species groups, 'A. purpurea' (mostly Atlantic) and 'A. smithi' (Indo-West Pacific). The 'A. purpurea' species group consists of two major molecular clades A. pelagica and A. kingsleyi - A. purpurea - A. quadrispinosa. Molecular data suggest that hitherto accepted species A. acanthitelsonis, A. pelagica, and A. sica should be considered as synonyms. The Atlantic is inhabited by at least two cryptic genetic lineages of A. pelagica and A. quadrispinosa. Morphological analyses of qualitative and quantitative (900 measurements) characters resulted in a tabular key to species and in a finding of four evolutionary traits. Atlantic species showed various scenarios of diversification visible on mitochondrial gene level, nuclear gene level, and morphological level. We recorded and discussed similar phylogeographic trends in diversification and in distribution of genetic lineages within two different clades: A. pelagica and A. kingsleyi - A. purpurea - A. quadrispinosa.

Morphology, genetic characterization and phylogeny of Moniliformis tupaia n. sp. (Acanthocephala: Moniliformidae) from the northern tree shrew Tupaia belangeri chinensis Anderson (Mammalia: Scandentia).

A new species of Moniliformis, M. tupaia n. sp. is described using integrated morphological methods (light and scanning electron microscopy) and molecular techniques (sequencing and analysing the nuclear 18S, ITS, 28S regions and mitochondrial cox1 and cox2 genes), based on specimens collected from the intestine of the northern tree shrew Tupaia belangeri chinensis Anderson (Scandentia: Tupaiidae) in China. Phylogenetic analyses show that M. tupaia n. sp. is a sister to M. moniliformis in the genus Moniliformis, and also challenge the systematic status of Nephridiacanthus major. Moniliformis tupaia n. sp. represents the third Moniliformis species reported from China.

First molecular description of Neorhadinorhynchus nudus (Acanthocephala: Cavisomidae) from fish in the pacific coast of Vietnam, with notes on biogeography.

Neorhadinorhynchus nudus (Harada, 1938) Yamaguti, 1939 (Cavisomidae) was morphologically described from the frigate tuna Auxis thazard (Lacépède) (Scombridae) in Nha Trang, Pacific south Vietnam. Females of N. nudus were fully described for the first time in the Pacific. Its original inadequate description as Rhadinorhynchus nudus (Harada, 1938) was corrected in material from Fiji Island, the Red Sea and Pacific Vietnam and errors in the text and line drawings of Harada were repeated in subsequent major publications where it underwent considerable nomenclature changes. New descriptive and biogeographical notes are included. We also provided here the molecular characterization of the nuclear gene (18S) and the mitochondrial cytochrome c oxidase subunit 1 (cox1) sequence data of N. nudus. Furthermore, to elucidate the phylogenetic relationship of N. nudus within the family Cavisomidae and with other isolates were performed incorporating nuclear (18S) and mitochondrial (cox1) sequence data using maximum likelihood (ML) and Bayesian inference (BI). The phylogenetic results showed that N. nudus has a relationship with other isolates of the same species and the median-joining network showed the pattern of haplotypes that reflected the structure of the populations.

The discovery of Moniliformis saudi (Acanthocephala: Moniliformidae) in the Algerian hedgehog Atelerix algirus in Malta: morphological, molecular, and metal analyses.

The acanthocephalan Moniliformis saudi Amin, Heckmann, Mohammed, Evans, 2016 was originally described from the desert hedgehog, Paraechinus aethiopicus (Ehrenberg) in central Saudi Arabia. The distribution of P. aethiopicus extends to North Africa and west to Mauritania. Moniliformis saudi was recently found in the Algerian hedgehog Atelerix algirus (Lereboullet) in Malta. The distribution of A. algirus is restricted to the North African and east Iberian Mediterranean coast and associated islands. Both host species cohabit and share the same feeding grounds in northern Algeria where common infections appear to take place. The morphology of specimens from both acanthocephalan populations was similar, with minor variations mostly related to the relatively larger Maltese specimens especially the trunk and the male reproductive system. Taxonomic features like the cone-shaped anterior trunk, size and formula of proboscis and hooks, the receptacle, size and shape of eggs, anatomy of the apical proboscis sensory pores, and the stellate body wall giant nuclei were, however, practically identical. SEM and microscope images of specimens of the Maltese population emphasize their qualitative characteristics such as the degree of the extreme spiral muscle development and the development of the posterior nucleated pouches of the proboscis receptacle. Proboscis hooks of specimens from both the Maltese and the Saudi populations had similarly high levels (percent weights) of calcium, moderate levels of phosphorus, and minimal levels of sulfur, magnesium and sodium marking the diagnostic value of the Energy Dispersive x-ray analysis in species recognition. Newly generated partial sequences of the 18S ribosomal RNA and cytochrome C oxidase subunit 1 (Cox1) of the mitochondrial gene were generated from M. saudi from Malta. Moniliformis saudi from Malta, when compared with other available sequences of the same species isolates available in the GenBank database, formed a strongly supported clade with other congeners. The comparison of the molecular profiles of specimens from populations in Malta, Spain, and Saudi Arabia shows no or low genetic variation between them. Ultimately, we provide a morphological and molecular description of a new population of M. saudi from a new host species in a new geographical location, vastly exceeding the originally described ones from Saudi Arabia. A Cox 1 haplotype network inferred with 10 sequences revealed the presence of eight haplotypes, one of which was shared between the populations of Malta and Spain of M. saudi.

Characterization of the complete mitochondrial genomes of the zoonotic parasites Bolbosoma nipponicum and Corynosoma villosum (Acanthocephala: Polymorphida) and the molecular phylogeny of the order Polymorphida.

Acanthocephalans of the order Polymorphida mainly parasitic in birds and mammals, are of veterinary, medical and economic importance. However, the evolutionary relationships of its 3 families (Centrorhynchidae, Polymorphidae and Plagiorhynchidae) remain under debate. Additionally, some species of Polymorphida (i.e. Bolbosoma spp. and Corynosoma spp.) are recognized as zoonotic parasites, associated with human acanthocephaliasis, but the mitochondrial genomes for representatives of Bolbosoma and Corynosoma have not been reported so far. In the present study, the complete mitochondrial genomes B. nipponicum and C. villosum (Acanthocephala: Polymorphidae) are reported for the first time, which are 14 296 and 14 241 bp in length, respectively, and both contain 36 genes [including 12 PCGs, 22 tRNA genes and 2 rRNA genes] and 2 non-coding regions (NCR1 and NCR2). The gene arrangement of some tRNAs in the mitogenomes of B. nipponicum and C. villosum differs from that found in all other acanthocephalans, except Polymorphus minutus. Phylogenetic results based on concatenated amino acid (AA) sequences of the 12 protein-coding genes (PCGs) strongly supported that the family Polymorphidae is a sister to the Centrorhynchidae rather than the Plagiorhynchidae, and also confirmed the sister relationship of the genera Bolbosoma and Corynosoma in the Polymorphidae based on the mitogenomic data for the first time. Our present findings further clarified the phylogenetic relationships of the 3 families Plagiorhynchidae, Centrorhynchidae and Polymorphidae, enriched the mitogenome data of the phylum Acanthocephala (especially the order Polymorphida), and provided the resource of genetic data for diagnosing these 2 pathogenic parasites of human acanthocephaliasis.

Integrative taxonomy of Serrasentis gibsoni n. sp. (Acanthocephala: Isthmosacanthidae) from flatfishes in the Gulf of Mexico.

The Isthmosacanthidae acanthocephalan species of the genus Serrasentis are parasites of marine teleosts and an elasmobranch. In this study, Serrasentis gibsoni n. sp. is described from the intestines of four flatfish species (Paralichthyidae), namely Ancyclopsetta quadrocellata, Cyclopsetta chittendeni, Syacium gunteri, and S. papillosum from 10 oceanic sites in the Gulf of Mexico (GoM). Twenty sequences of the 'barcoding' region of cytochrome C oxidase subunit I gene were obtained from 20 adults of Serrasentis gibsoni n. sp. Additionally, five sequences of the barcoding region were obtained from five adults of rhadinorhynchid Gorgorhynchus lepidus from C. chittendeni, S. papillosum and one species of Haemulidae, Haemulom aurolineatum, from five oceanic sites from the GoM. Two phylogenetic approaches were followed: Bayesian inference and maximum likelihood. In both phylogenetic reconstructions, the sequences of Serrasentis gibsoni n. sp. were recovered as a monophyletic group within the genus Serrasentis and placed as a sister group to G. lepidus. However, due to the lack of molecular data for species of the Isthmosacanthidae and Rhadinorhynchidea, these phylogenetic inferences must be taken with caution. Serrasentis gibsoni n. sp. is the first species of Serrasentis described from Paralichthyidae flatfish species from marine waters of the Americas and from the GoM. Based on the barcoding data set analyzed, Serrasentis gibsoni n. sp. appears to have high intraspecific genetic variation; thus, it is necessary to continue exploring the genetic diversity of this species to infer its intraspecific evolutionary patterns.

Morpho-molecular characterisation of two new and two previously reported species of Acanthogyrus (Acanthogyrus: Quadrigyridae) from freshwater fishes in India.

Of the total 47 species in the subgenus Acanthosentis, 43 have been reported from the freshwater fishes of Asia. Amin et al. (2017) provided a key to the 23 species of the genus Acanthogyrus reported from the Indian subcontinent. The present study reports two new species: Acanthogyrus bispinosa n. sp. and A. garciai n. sp. from Cirrhinus mrigala Hamilton and Labeo calbasu Hamilton, respectively, and two previously described species: A. golvani Gupta and Jain, 1980 and A. hereterospinus Khan and Bilqees, 1990 from L. rohita Hamilton and L. catla Hamilton, respectively. A. bispinosa n. sp. comprises 3 circles of 6 proboscis hooks each. Trunk spines in A. bispinosa n. sp are divided into two groups: anterior and posterior separated by unarmed region, which has not been previously reported in the subgenus. Anterior spines are present in 7-8 and 7-10 circles in females and males, respectively, whereas posterior spines are in 23-28 and 31-38 circles in males and females, respectively. A. garciai n. sp. comprises 3 circles of 6-8 hooks each and a single set of trunk spines is present in A. garciai n. sp., comprising 35-42 and 25-45 circles in males and females, respectively. All four species were also characterised based on the 18S, 28S, and ITS1-5.8S-ITS2 rRNA molecular markers. The Bayesian inference tree generated based on these markers showed distinct identities of all the species, with a significant molecular divergence, ranging from 3.2 to 53.6%.

Characterization of the complete mitochondrial genome of Acanthogyrus (Acanthosentis) bilaspurensis Chowhan, Gupta & Khera, 1987 (Eoacanthocephala: Quadrigyridae), the smallest mitochondrial genome in Acanthocephala, and its phylogenetic implications.

The phylum Acanthocephala is an important group of parasites with more than 1,300 species parasitizing intestine of all major vertebrate groups. However, our present knowledge of the mitochondrial genomes of Acanthocephala remains very limited. In the present study, we sequenced and annotated the complete mitochondrial genome of Acanthogyrus (Acanthosentis) bilaspurensis (Gyracanthocephala: Quadrigyridae) for the first time based on the specimens recovered from the intestine of common carp Cyprinus carpio Linnaeus (Cyprinidae) in Pakistan. The mitochondrial genome of A. bilaspurensis is 13,360 bp in size and contains 36 genes, representing the smallest mitogenome of acanthocephalans reported so far. The mitogenome of A. bilaspurensis also has the lowest level of overall A+T contents (59.3%) in the mitogenomes of Eoacanthocephala, and the non-coding region 3 (NCR3) lies between trnS2 and trnI, which is different from all of the other acanthocephalan species. Phylogenetic analyses based on concatenating the amino acid sequences of 12 protein-coding genes using maximum likelihood (ML) and Bayesian inference (BI) methods revealed that the family Pseudoacanthocephalidae is a sister to the Arhythmacanthidae rather than the Cavisomatidae, and the families Rhadinorhynchidae and Cavisomatidae showed sister relationships.

Chromosome analysis and the occurrence of B chromosomes in fish parasite Acanthocephalus anguillae (Palaeacanthocephala: Echinorhynchida).

The cytogenetics of Acanthocephala is a neglected area in the study of this group of endoparasites. Chromosome number and/or karyotypes are known for only 12 of the 1,270 described species, and molecular cytogenetic data are limited to rDNA mapping in two species. The standard karyological technique and mapping of 18S rRNA and H3 histone genes on the chromosomes of Acanthocephalus anguillae individuals from three populations, one of which originated from the unfavorable environmental conditions of the Zemplínska Sírava reservoir in eastern Slovakia, were applied for the first time. All specimens had 2n = 7/8 (male/female); n = 1m + 1m-sm + 1a + 1a (X). Fluorescence in situ hybridization (FISH) revealed three loci of 18S rDNA on two autosomes and dispersion of H3 histone genes on all autosomes and the X chromosome. In addition to the standard A chromosome set, 34% of specimens from Zemplínska Sírava possessed a small acrocentric B chromosome, which was always found to be univalent, with no pairing observed between the B chromosome and the A complement. The B chromosome had a small amount of heterochromatin in the centromeric and telomeric regions of the chromosomal arms and showed two clusters of H3 genes. It is well known that an environment permanently polluted with chemicals leads to an increased incidence of chromosomal rearrangements. As a possible scenario for the B chromosome origin, we propose chromosomal breaks due to the mutagenic effect of pollutants in the aquatic environment. The results are discussed in comparison with previous chromosome data from Echinorhynchida species.

Title: Analyse chromosomique et présence de chromosomes B chez le parasite de poisson Acanthocephalus anguillae (Palaeacanthocephala, Echinorhynchida). Abstract: La cytogénétique des Acanthocephala est un domaine négligé dans l'étude de ce groupe d'endoparasites. Le nombre de chromosomes et/ou les caryotypes ne sont connus que pour 12 des 1270 espèces décrites, et les données cytogénétiques moléculaires se limitent à la cartographie de l'ADNr chez deux espèces. La technique caryologique standard et la cartographie des gènes de l'ARNr 18S et de l'histone H3 ont été appliquées pour la première fois sur les chromosomes d'individus d'Acanthocephalus anguillae provenant de trois populations, dont l'une dans les conditions environnementales défavorables du réservoir de Zemplínska Sírava dans l'est de la Slovaquie. Tous les spécimens avaient 2n = 7/8 (mâle/femelle); n = 1m + 1m-sm + 1a + 1a (X). La technique FISH a révélé trois locus d'ADNr 18S sur deux autosomes et une dispersion des gènes de l'histone H3 sur tous les autosomes et sur le chromosome X. En plus de l'ensemble standard de chromosomes A, 34 % des spécimens de Zemplínska Sírava possédaient un petit chromosome B acrocentrique, qui s'est toujours révélé univalent, sans aucun appariement observé entre le chromosome B et le complément A. Le chromosome B avait une petite quantité d'hétérochromatine dans les régions centromériques et télomériques des bras chromosomiques et présentait deux groupes de gènes H3. Il est bien connu qu'un environnement pollué en permanence par des produits chimiques entraîne une incidence accrue de réarrangements chromosomiques. Comme scénario possible pour l'origine du chromosome B, nous proposons des cassures chromosomiques dues à l'effet mutagène des polluants du milieu aquatique. Les résultats sont discutés en comparaison avec les données chromosomiques précédentes des espèces d'Echinorhynchida.

Description and molecular data for a new acanthocephalan parasite, Polymorphus circi n. sp. (Polymorphidae) from the Australasian harrier (Circus approximans Peale) in New Zealand.

Species of genus Polymorphus Lühe, 1911 (Polymorphidae) are acanthocephalans found in fish-eating birds and waterfowl. Although found in many parts of the world, including Australia, no records exist from New Zealand. Because of the largely aquatic intermediate host, Polymorphus species are rarely found in terrestrial birds of prey. During a study of the helminths of the Australasian harrier Circus approximans Peale specimens of Polymorphus were recovered that were found to be new to science. Polymorphus circi n. sp. is formally described and genetic sequence data presented. Specimens were distinguished from all other species by a combination of characters, including their proboscis hook arrangement (20-22 rows of 11-13 hooks), as well as absence of sexual dimorphism, trunk size, proboscis shape and egg size. These acanthocephalans were found in birds from areas with the potential to support freshwater, brackish or marine amphipods, but as yet the actual intermediate hosts are unknown.

Hooking the scientific community on thorny-headed worms: interesting and exciting facts, knowledge gaps and perspectives for research directions on Acanthocephala.

Although interest in Acanthocephala seems to have reached only a small community of researchers worldwide, we show in this opinion article that this group of parasites is composed of excellent model organisms for studying key questions in parasite molecular biology and cytogenetics, evolutionary ecology, and ecotoxicology. Their shared ancestry with free-living rotifers makes them an ideal group to explore the origins of the parasitic lifestyle and evolutionary drivers of host shifts and environmental transitions. They also provide useful features in the quest to decipher the proximate mechanisms of parasite-induced phenotypic alterations and better understand the evolution of behavioral manipulation. From an applied perspective, acanthocephalans' ability to accumulate contaminants offers useful opportunities to monitor the impacts - and evaluate the possible mitigation - of anthropogenic pollutants on aquatic fauna and develop the environmental parasitology framework. However, exploring these exciting research avenues will require connecting fragmentary knowledge by enlarging the taxonomic coverage of molecular and phenotypic data. In this opinion paper, we highlight the needs and opportunities of research on Acanthocephala in three main directions: (i) integrative taxonomy (including non-molecular tools) and phylogeny-based comparative analysis; (ii) ecology and evolution of life cycles, transmission strategies and host ranges; and (iii) environmental issues related to global changes, including ecotoxicology. In each section, the most promising ideas and developments are presented based on selected case studies, with the goal that the present and future generations of parasitologists further explore and increase knowledge of Acanthocephala.

Title: Accrocher la communauté scientifique à des vers à la tête pleine d'épines : faits intéressants et passionnants, lacunes dans les connaissances et perspectives pour des orientations de recherche sur les Acanthocéphales. Abstract: Bien que l'intérêt pour les acanthocéphales semble n'avoir atteint qu'un petit nombre de chercheurs dans le monde, nous montrons dans cet article que ce groupe de parasites est composé d'excellents organismes modèles pour étudier les questions en suspens en biologie moléculaire et cytogénétique, écologie évolutive et écotoxicologie. Leur ascendance partagée avec les rotifères en fait un groupe idéal pour explorer les origines du mode de vie parasitaire et les moteurs évolutifs des changements d'hôtes et des transitions environnementales. Ils présentent également des caractéristiques intéressantes pour l'étude des mécanismes proximaux sous-tendant les altérations phénotypiques induites par les parasites, et ainsi mieux comprendre l'évolution de la manipulation comportementale. D'un point de vue appliqué, la capacité des acanthocéphales à accumuler les contaminants offre des opportunités utiles pour surveiller les impacts - et évaluer les possibilités d'atténuation - des pollutions anthropiques sur la faune aquatique et développer le domaine de la parasitologie environnementale. Cependant, l'exploration de ces pistes de recherche passionnantes nécessitera de relier des connaissances fragmentaires en élargissant la couverture taxonomique des données moléculaires et phénotypiques. Dans cet article, nous présentons l'état actuel de la recherche sur les acanthocéphales selon trois axes principaux : (i) la taxonomie intégrative (y compris les outils non-moléculaires) et la phylogénie à des fins d'analyse comparative ; (ii) l'écologie et l'évolution des cycles de vie, des stratégies d'exploitation des hôtes et de transmission ; (iii) les questions environnementales liées aux changements globaux, y compris l'écotoxicologie. Dans chaque section, nous soulignons les besoins et les opportunités, en espérant que cela incitera une nouvelle génération de parasitologues à s'intéresser aux acanthocéphales.

The mitochondrial genome of Heterosentis pseudobagri (Wang & Zhang, 1987) Pichelin & Cribb, 1999 reveals novel aspects of tRNA genes evolution in Acanthocephala.

BACKGROUND: Acanthocephala is a clade of obligate endoparasites whose mitochondrial genomes (mitogenomes) and evolution remain relatively poorly understood. Previous studies reported that atp8 is lacking from acanthocephalan mitogenomes, and that tRNA genes often have nonstandard structures. Heterosentis pseudobagri (Arhythmacanthidae) is an acanthocephalan fish endoparasite for which no molecular data are currently available, and biological information is unavailable in the English language. Furthermore, there are currently no mitogenomes available for Arhythmacanthidae. METHODS: We sequenced its mitogenome and transcriptome, and conducted comparative mitogenomic analyses with almost all available acanthocephalan mitogenomes. RESULTS: The mitogenome had all genes encoded on the same strand and unique gene order in the dataset. Among the 12 protein-coding genes, several genes were highly divergent and annotated with difficulty. Moreover, several tRNA genes could not be identified automatically, so we had to identify them manually via a detailed comparison with orthologues. As common in acanthocephalans, some tRNAs lacked either the TWC arm or the DHU arm, but in several cases, we annotated tRNA genes only on the basis of the conserved narrow central segment comprising the anticodon, while the flanking 5' and 3' ends did not exhibit any resemblance to orthologues and they could not be folded into a tRNA secondary structure. We corroborated that these are not sequencing artefacts by assembling the mitogenome from transcriptomic data. Although this phenomenon was not observed in previous studies, our comparative analyses revealed the existence of highly divergent tRNAs in multiple acanthocephalan lineages. CONCLUSIONS: These findings indicate either that multiple tRNA genes are non-functional or that (some) tRNA genes in (some) acanthocephalans might undergo extensive posttranscriptional tRNA processing which restores them to more conventional structures. It is necessary to sequence mitogenomes from yet unrepresented lineages and further explore the unusual patterns of tRNA evolution in Acanthocephala.

Cryptic diversity in a gastrointestinal acanthocephalan of New World primates from Costa Rica.

Prosthenorchis elegans is a worm of the family Archiacanthocephala that infects non-human primates in the Americas, producing an intestinal pathology that may compromise the life of its hosts. Squirrel monkeys, Saimiri oerstedii citrinellus, were found with P. elegans in Costa Rica. Histopathological analysis revealed a severe pyogranulomatous response composed by macrophages, neutrophils, eosinophils, fibroblasts and lymphocytes. Morphological worm analyses revealed 36 hooks in the proboscis distributed in six rows; and total body, hook and lemnisci length were compatible to the original descriptions of P. elegans. In addition, phylogenetic, haplotype network and genetic distance analyses were done on cytochrome oxidase subunit 1, cox1, sequences obtained from the collected specimens. Sequences obtained herein clustered separately with high posterior probabilities in a Bayesian Inference tree and showed 8.12% nucleotide differences when compared to P. elegans from Colombia. This high divergence was confirmed in the TCS network that separated Colombian and Costa Rican sequences by 32 mutational steps, a genetic distance PCA which separated sequences from both geographical locations by 89.5% and an FST value of 0.655, indicating the presence of cryptic diversity in P. elegans. Additional studies from specimens collected from other definitive hosts and geographical locations are required to better understand the biodiversity of this species.

Morphological and Molecular Characterization of Two New and Two Already Known Species of the Genus Pallisentis (Acanthocephala: Quadrigyridae) from India with an Update in Key to the Species.

To date, 31 species assigned to the genus Pallisentis Van cleave, 1928 have been reported from India. The present study includes morphological and molecular descriptions of two new species of Pallisentis Van Cleave, 1928, namely P. himachalensis and P. longus from the fresh water fishes Channa punctata (Bloch, 1793) and C. marulius (Hamilton, 1822), respectively, procured from Himachal Pradesh and Chandigarh, India. Of total 35 fishes, 17 were found infected with acanthocephalan parasites. The prevalence of infection was 42.85 and 52.38% for C. punctata and C. marulius, respectively. The morphological characters of P. himachalensis n. sp. include proboscis with 4 circles of hooks with 810 hooks per circle, which gradually decline in size. The trunk in male comprises 1516 circles of collar spines and 2737 circles of trunk spines ending above the anterior testis with syncytial cement gland having 2629 nuclei. The trunk in female comprises of 1418 circles of collar spines and 5573 circles of trunk spines present till the anterior end of reproductive system with additional 34 circles at the posterior end. P. longus n. sp. is the longest species reported in the genus and the length of female reach up to 44 mm. The proboscis comprises 4 circles of proboscis hooks with 910 hooks per circle. In males 1316 circles of the collar spines and 2731 circles of trunk spines are present with syncytial cement gland containing 2025 nuclei. The females are much longer with 1516 circles of collar spines and 6469 circles of trunk spines present till the posterior end. The study also reports two already described species: P. gomtii Gupta and Verma, 1980 from C. punctata and P. nandai Sarkar, 1953 from C. marulius. Total 12 sequences for 4 species have been generated based on 18S, 28S and ITS15.8SITS2 molecular markers. The 18S and ITS15.8SITS2 Bayesian inference trees generated in the present study showed distinct identities of all 4 species. Moreover, the Bayesian inference tree generated in the present study based on 18S showed the clustering of Pallisentis species in three different clades compared to the previous studies in which only two clades within the genus were reported. The molecular analysis showed the monophyletic origin of the genus Pallisentis and does not support subgeneric classification within the genus.

Identification of antiparasitic drug targets using a multi-omics workflow in the acanthocephalan model.

BACKGROUND: With the expansion of animal production, parasitic helminths are gaining increasing economic importance. However, application of several established deworming agents can harm treated hosts and environment due to their low specificity. Furthermore, the number of parasite strains showing resistance is growing, while hardly any new anthelminthics are being developed. Here, we present a bioinformatics workflow designed to reduce the time and cost in the development of new strategies against parasites. The workflow includes quantitative transcriptomics and proteomics, 3D structure modeling, binding site prediction, and virtual ligand screening. Its use is demonstrated for Acanthocephala (thorny-headed worms) which are an emerging pest in fish aquaculture. We included three acanthocephalans (Pomphorhynchus laevis, Neoechinorhynchus agilis, Neoechinorhynchus buttnerae) from four fish species (common barbel, European eel, thinlip mullet, tambaqui). RESULTS: The workflow led to eleven highly specific candidate targets in acanthocephalans. The candidate targets showed constant and elevated transcript abundances across definitive and accidental hosts, suggestive of constitutive expression and functional importance. Hence, the impairment of the corresponding proteins should enable specific and effective killing of acanthocephalans. Candidate targets were also highly abundant in the acanthocephalan body wall, through which these gutless parasites take up nutrients. Thus, the candidate targets are likely to be accessible to compounds that are orally administered to fish. Virtual ligand screening led to ten compounds, of which five appeared to be especially promising according to ADMET, GHS, and RO5 criteria: tadalafil, pranazepide, piketoprofen, heliomycin, and the nematicide derquantel. CONCLUSIONS: The combination of genomics, transcriptomics, and proteomics led to a broadly applicable procedure for the cost- and time-saving identification of candidate target proteins in parasites. The ligands predicted to bind can now be further evaluated for their suitability in the control of acanthocephalans. The workflow has been deposited at the Galaxy workflow server under the URL tinyurl.com/yx72rda7 .

Phylogeny and Life Cycles of the Archiacanthocephala with a Note on the Validity of Mediorhynchus gallinarum.

PURPOSE: The molecular profile of specimens of Mediorhynchus gallinarum (Bhalero, 1937) collected from chickens, Gallus gallus L. in Indonesia was analysed. The aim of this study was to assess the phylogenetic position of species of Mediorhynchus within the order Giganthorhynchida. METHODS: We used one mitochondrial gene (cytochrome oxidase 1) and one nuclear gene (18S ribosomal RNA) to infer phylogenetic relationships of class Archiacanthocephala. RESULTS: The COI and 18S rDNA genes sequences showed that M. gallinarum had low genetic variation and that this species is sister to Mediorhynchus africanus Amin, Evans, Heckmann, El-Naggar, 2013. The phylogenetic relationships of the Class Archiacanthocephala showed that it is not resolved but, however, were mostly congruent using both genes. A review of host-parasite life cycles and geographic distributions of Archiacanthocephala indicates that mainly small mammals and birds are definitive hosts, while termites, cockroaches, and millipedes are intermediate hosts. CONCLUSIONS: While the intermediate hosts have wide geographic distributions, the narrow distribution of the definitive hosts limit the access of archiacanthocephalans to a wider range of prospective hosts. Additional analyses, to increase taxonomic and character sampling will improve the development of a robust phylogeny and provide more stable classification. The results presented here contribute to better understanding of the ecological and evolutionary relationships that allow the host-parasite co-existence within the class Archiacanthocephala.

New morphological and molecular perspectives about Macracanthorhynchus hirudinaceus (Acanthocephala: Oligacanthorhynchidae) from wild boar, Sus scrofa Linn., in Ukraine.

We make new morphological observations not previously reported for the old acanthocephalan Macracanthorhynchus hirudinaceus (Pallas, 1781) Travassos, 1917, described for the first time about 240 years ago. Our specimens were collected from the wild boar, Sus scrofa Linn., in Ukraine in 2005. We provide comparative morphometrics with other populations from Ukraine, Union of Soviet Socialist Republics, Europe, Brazil and the United States of America. Our specimens from the Ukraine had the smallest trunk (110-120 mm long), longest and thickest hooks, with the third hook being the largest, largest eggs, and a proboscis wider than long. We document the morphology of the proboscis, apical organ, hooks, hook roots, sensory pores, micropores, and eggs with scanning electron microscopy for the first time. We also provide chemical analysis of hooks and eggs using energy-dispersive X-ray analysis, discuss its micropores, and provide a new molecular profile based on 18S rDNA from a European population for the first time. Edge of hook tips feature high levels of calcium and phosphorous but the high level of sulphur is mostly found in the cortical layer of eggs. One new partial 18S rDNA sequence (482 nt length) was generated from an adult specimen of M. hirudinaceus. We present the first 18S rDNA published sequence for this cosmopolitan acanthocephalan obtained from Europe. The amplified region corresponded to the approximate middle region of the small subunit ribosomal ribonucleic acid gene, which is ~1800 nt in length. This molecular contribution is especially valuable in light of the extreme scarcity of genetic information about species of Macracanthorhynchus and of the family Oligacanthorhynchidae as a whole.

First report of an egg-predator nemertean worm in crabs from the south-eastern Pacific coast: Carcinonemertes camanchaco sp. nov.

Nemertean worms belonging to the genus Carcinonemertes have been tied to the collapse of crab fisheries in the northeastern Pacific Ocean. A new species is described from egg masses of two commercial crabs, Cancer porteri and Romaleon setosum, inhabiting the central-north Chilean coast. This is the first species of Carcinonemertes described from the southeastern Pacific Ocean. Total body length of Carcinonemertes camanchaco sp. nov. ranged from 2.38 to 4.93 and from 4.29 to 8.92 mm, in males and females, respectively. Among others, traits that distinguish this new species from other previously described congeneric species include: presence of two gonad rows on each side of the intestine, a simple (not decorated) mucus sheath, and a relatively wide stylet basis. Maximum likelihood and Bayesian inference phylogenetic analyses distinguished this new species from all other species of Carcinonemertes with available cox1 sequences in GenBank. Prevalence and mean (± SD) intensity of C. camanchaco sp. nov. was 24% and 2.6 (± 2.07) worms per egg mass in C. porteri and 38.1% and 3.8 (± 2.4) worms per egg mass in R. setosum. The formal description of this new species represents the first step towards the understanding of this worm's impact on the health of crab fisheries in the southeastern Pacific Ocean.

New insights on Pomphorhynchus sphaericus Gil de Pertierra, Spatz et Doma, 1996 (Acanthocephala: Pomphorhynchidae).

The finding of Pomphorhynchus sphaericus in new localities from La Plata River allowed the reevaluation of the species using a taxonomic integrative approach. The newly found specimens in Pimelodus maculatus from Samborombon Bay differ from P. sphaericus by the roots of hooks 1-6 which not form a wide sheet split into 2 apophysis, the slender, separated and equatorial testicles, the position of the cement glands, the shape of the proboscis, the shape and length of lemnisci, and the eggs size. Despite the notorious observed morphological differences, the COI mtDNA analysis confirmed that Pomphorhynchus individuals are the same conspecific, and showed that there is a high phenotypical plasticity in this species. Pomphorhynchus sphaericus is the first South American species analyzed to a DNA level (COI mtDNA, ITS, and 18S rDNA genes). The molecular analysis relates P. sphaericus to P. bulbocolli and P. purhepechus.

MOLECULAR IDENTIFICATION OF JUVENILE NEOECHINORHYNCHUS SPP. (PHYLUM: ACANTHOCEPHALA) INFECTING OSTRACOD AND SNAIL HOSTS PROVIDES INSIGHT INTO ACANTHOCEPHALAN HOST USE.

The role of invertebrates in some acanthocephalan life cycles is unclear because juvenile acanthocephalans are difficult to identify to species using morphology. Most reports suggest acanthocephalans from turtle definitive hosts use ostracods as intermediate hosts and snails as paratenic hosts. However, laboratory studies of the life cycle suggest that ostracods and snails are both required hosts in the life cycle. To elucidate the role of ostracods and snails in acanthocephalan life cycles better, we collected 558 freshwater snails of 2 species, including Planorbella cf. Planorbella trivolvis and Physa acuta, from 23 wetlands in Oklahoma, U.S.A., and examined them for acanthocephalan infections. Additionally, we examined 37,208 ostracods of 4 species, Physocypria sp. (morphotype 1), Cypridopsis sp., Stenocypris sp., and Physocypria sp. (morphotype 2) for juvenile acanthocephalans from 2 wetlands in Oklahoma. Juvenile acanthocephalans were morphologically characterized, and the complete internal transcribed spacer (ITS) region of nuclear rDNA was sequenced from acanthocephalans infecting 11 ostracod and 13 snail hosts. We also sampled 10 red-eared slider turtles, Trachemys scripta elegans, and 1 common map turtle, Graptemys geographica, collected from Oklahoma, Arkansas, and Texas and recovered 1,854 adult acanthocephalans of 4 species. The ITS of 17 adult acanthocephalans of 4 species from turtle hosts were sequenced and compared to juvenile acanthocephalan sequences from ostracod and snail hosts from this study and GenBank to determine conspecificity. Of the 23 locations sampled for snails, 7 (30%) were positive for juvenile acanthocephalans in the genus Neoechinorhynchus. The overall prevalence and mean intensity of acanthocephalans in Planorbella cf. P. trivolvis and P. acuta were 20% and 2 (1-6) and 2% and 1 (1), respectively. In contrast, only 1 of 4 species of ostracods, Physocypria sp. (morphotype 1), was infected with larval/juvenile Neoechinorhynchus spp. with an overall prevalence of 0.1% and a mean intensity of 1 (1-2). Although 4 species of acanthocephalans infected turtle definitive hosts, including Neoechinorhynchus chrysemydis, Neoechinorhynchus emydis, Neoechinorhynchus emyditoides, and Neoechinorhynchus pseudemydis, all the ITS sequences from cystacanths infecting snail hosts were conspecific with N. emydis. In contrast, the ITS sequences from larval/juvenile acanthocephalans from ostracods were conspecific with 2 species of acanthocephalans from turtles (N. emydis and N. pseudemydis) and 1 species of acanthocephalan from fish (Neoechinorhynchus cylindratus). These results indicate that N. emydis infects freshwater snails, whereas other species of Neoechinorhynchus appear not to infect snail hosts. We document new ostracod and snail hosts for Neoechinorhynchus species, including the first report of an ostracod host for N. pseudemydis, and we provide novel molecular barcodes that can be used to determine larva, juvenile, and adult conspecificity of Neoechinorhynchus species.